/**
 * Copyright (c) 2009, Microsoft
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of Microsoft nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY Microsoft ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL Microsoft BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @category   Microsoft
 * @package    WebErrorPHPToolkit
 * @subpackage Error
 * @version    $Id: document_helper.js, v 1.0 2009-10-09 08:00:00Z unknown $
 * @copyright  Copyright (c) 2009, Microsoft (http://www.microsoft.com)
 * @author     a-jetann
 *
 * Support functions for DOM.document.
 */
 

/**
 * Get valid document element, and if not valid throw exception.
 *
 * @param id string Element ID
 * @param fail_throw boolean Throw exception if element is undefined.
 * @return document element.
 * @throw Exception if element is undefined.
 */
function getValidElementById (id, fail_throw )
{
  fail_throw = typeof(fail_throw) != 'undefined' ? fail_throw : true;

  var element = document.getElementById(id);
  if (isNull(element))
  {
    if (fail_throw)
    {
      throw new Error("Element '"+id+"' is not defined.");
    }
    
    return false;
  }
  
  return element;
};

/**
 * Get value of valid document element.
 *
 * @param id string Element ID
 * @param fail_throw boolean Throw exception if element is undefined.
 * @return mixed Element value.
 */
function getValueByElementId(id, fail_throw)
{
  fail_throw = typeof(fail_throw) != 'undefined' ? fail_throw : true;
  var element = getValidElementById(id, fail_throw);
  return isNull(element) ? null : element.value;
};

/**
 * Set value of valid document element.
 *
 * @param id string Element ID
 * @param value mixed
 * @param fail_throw boolean Throw exception if element is undefined.
 * @return void
 */
function setValueByElementId(id, value, fail_throw)
{
  fail_throw = typeof(fail_throw) != 'undefined' ? fail_throw : true;
  var element = getValidElementById(id, fail_throw); 
  if (!isNull(element))
  {
    element.value = value;
  }
};